This invention relates to a continuous mixer for liquids that can continuously mix a single incoming liquid or two or more incoming liquids.
The continuous mixing of one or more liquid stocks is widely practiced in the rubber molding industry and plastic molding industry. An example of this is the mixing of a base and curing agent in order to fabricate a foamed gasket.
For example, Japanese Patent Publication (Kokoku) Number Sho 53-15942 (15,942/1978), "Nozzle for mixing fluid components", teaches a nozzle for mixing a plurality of fluid components that react upon mixing with a rapid increase in viscosity or else cure upon mixing. The nozzle taught in this reference comprises a housing with a conical interior surface and a conical rotor that is rotated at its center on the axis within said housing. The surface of the rotor is provided with concavities, fins, and grooves. This nozzle can continuously mix a plural number of reactive fluid components in the absence of solvent.
The "Resin extrusion apparatus having a rotating conical element" disclosed in Japanese Patent Application Laid Open (Kokai) Number Hei 2-43008 (43,008/1990) comprises a rotating element whose exterior surface is a conical surface and whose rotational axis is the central axis thereof and a fixed element having a conical interior surface that faces the aforesaid rotating conical surface across a narrow gap. The design is such that rotation of the rotating element causes resin raw materials to be mixed in and extruded through the gap between the conical surfaces of the rotating and fixed elements.
The "Method for fabricating foam gaskets" disclosed in Japanese Patent Application Laid Open (Kokai) Number Hei 3-94876 (94,876/1991) employs a mixing chamber that is equipped internally with a surface-grooved rotating element and that has a nozzle formed at its bottom. The two liquids making up a two-part foamable plastic (the base and curing agent) are separately transported into this mixing chamber and mixed therein, and the resulting liquid mixture is discharged from the nozzle onto the sealing region of the particular substrate.
The "Apparatus for preparing silicone foam" of Japanese Patent Application Laid Open (Kokai) Number Hei 6-99509 (99,509/1994) solves a problem occurring with Japanese Patent Application Laid Open Number Hei 3-94876 in that the interior of the mixing chamber and nozzle element of the applicator must be cleaned with solvent after each application cycle. In the former a preheater is provided on the circumference of a liquid delivery hose that runs from the mixer to the discharge nozzle.
Several means have been employed or attempted in prior art apparatuses for continuously mixing liquids in order to control the temperature and pressure within the mixer during mixing into prescribed ranges or control the size of particulates within the mixed liquid. These means include:
(1) installation of a thermal medium jacket on the casing of the mixing apparatus and adjustment of the temperature and flow-rate of the thermal medium in the jacket (thermal medium control); PA0 (2) adjustment of the rotation rate of the rotor in the mixing apparatus (rotor rotation control); PA0 (3) pressure control through installation of a throttle on the mixed liquid outlet from the mixing apparatus (throttle control); and PA0 (4) adjustment in the input feed amounts (input flow-rate control).
These prior art means described above suffer from various problems. Temperature control by thermal medium control (1) has a poor response. In the case of rotor rotation control (2), a change in rotor rpm ends up causing a change in the intensity of mixing imparted to the mixing inputs. In the case of throttle control (3), the installation of a throttle at the outlet increases the resident amount of the input. The drawback to input flow-rate control (4) is that variations in the material feed also affect upstream and downstream processes. Moreover, a rapid response and high accuracy are required in order to regulate the internal temperature and pressure in the mixer in particular when a rapid chemical reaction is produced upon mixing (for example, in the case of curing by reaction). However, the prior art technologies are unable to satisfy this requirement. Another drawback to the prior art technologies is that they cannot regulate the particle size within the mixed liquid when the liquid input contains particulate.
The present invention was developed in order to solve the various problems described above. Specifically, the object of the present invention is to provide a continuous mixer for liquids that can continuously mix a single or several liquid inputs and that is capable of a highly responsive and very precise control of the temperature and pressure of the mixed liquid afforded by the liquid input. Another object of the present invention is to provide a continuous mixer for liquids which can control the temperature and pressure of the mixed liquid produced from the liquid input, which does not cause variations in the intensity of mixing of the mixed liquid, which minimizes the resident amount of the inputs, and which has little effect on upstream and downstream processes. A further object of the present invention is to provide a continuous mixer for liquids that can regulate the particle size in the mixed liquid from the liquid input in combination with regulation of the temperature and pressure.
The aforesaid objects are achieved by having the rotor of a continuous mixer assume the form of a cone or truncated cone centered on the axis of rotation with the mixed liquid discharge side at its vertex; having the interior surface of the casing of the mixer assume the form of a truncated cone that matches the shape of the rotor; setting the vertical angle of the truncated cone casing equal to or not substantially different from the vertical angle of the rotor; axially displacing the rotor or casing along the rotation axis; and thereby adjusting the gap between the rotor and casing.